Abstract

We demonstrate enhanced relaxation and dephasing times of transmon qubits, up to , by fabricating the interdigitated shunting capacitors using titanium nitride (TiN). Compared to qubits made with lift-off aluminum deposited simultaneously with the Josephson junction, this represents as much as a six-fold improvement and provides evidence that surface losses from two-level system (TLS) defects residing at or near interfaces contribute to decoherence. Concurrently, we observe an anomalous temperature dependent frequency shift of TiN resonators, which is inconsistent with the predicted TLS model.

Received 15 May 2013Accepted 18 June 2013Published online 03 July 2013

Acknowledgments:

The authors would like to thank E. Duch, R. Martin, and E. O'Sullivan for their contributions to this work, and Chris Lirakis, Jim Rozen, and Jack Rohrs for their support. The authors acknowledge useful comments on the manuscript from S. Poletto, E. Lucero, N. Masluk, and D. McClure. Portions of this work were completed in the IBM T. J. Watson Microelectronics Research Laboratory. This work was supported by DARPA and the NIST Quantum Information Program. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressly or implied, of the Defense Advanced Research Projects Agency.